A good duet is founded on good player decisions, which requires the narrator to cultivate the conditions that encourage the player to make good decisions. This is the secret recipe for successful duet campaigns. The challenge is realizing that not all decisions are the same and thus the conditions that you need to establish vary by the situation. it is imperative that you give thought to the challenges you present to the player to make the most of them.

Generally, there are the following types of decisions: directional, moral, and tactical. We'll cover them in reverse order.

Tactical decisions are how the player navigates discrete obstacles during a campaign. This is classic roleplaying stuff: defeating an ogre, crossing a chasm, piloting a starfighter through the asteroid field, etc. Almost all RPGs focus 90% of their attention, and rules, on these decisions, which require the player to maneuver here, use ability X there, gain a bonus by using that, and so forth to gain the best odds of success for an action. This is an area that most RPGs cover very extensively so there's no real reason to discuss them further save to make the following point about social challenges:

I am firmly on the side that believes social challenges should not be resolved by a dice roll and instead should be roleplayed out. This is especially true in duets, which flourish with roleplaying. You can have a great duet with almost no combat but you can never have a great duet without a lot of roleplaying. I also have never understood the need to dumb down social interactions which anyone can manage through roleplaying. Admittedly, in a group setting this is sometimes necessary - such as if the narrator isn't particularly fair or you have a group with some shy players - but with duets these shouldn't be factors. Just let the player roleplay the situation out, and then you as narrator make a fair decision, generally giving the player the benefit of the doubt. If the player botches the situation, then the player botches it. It's really no different than relying upon a dice roll, except that if you require roleplaying the player will have more control over the outcome.

Moral decisions are the best decisions you can foist upon a player. Generally, there isn't always a 'right' or 'wrong' answer and a good moral crisis is rich for roleplaying and engaging with a setting. There may also be potent consequences to rival that of any tactical decision so the stakes can be quite high. In general, moral decisions are what define a duet campaign.

A good moral crisis has a few elements. First, there must be significant stakes to the crisis. Second, there must be genuine choices. Third, the PC must be empowered to have the authority to make a decision.

Consider the following scenarios:

• A beggar asks for some coins.
• An escaped convicted murderer seeks refuge with the PC.
• An evil lord seeks an alliance with the PC to betray his family.

Moral crises? No, not really. It may seem that way at first but there isn't any depth or substance to these. Moral challenges are like tactical challenges in that they're scaleable. It is the narrator's responsibility to push and test the player.

Consider these instead:

• A beggar comes up and asks for some coin or he might let slip out what he overhead the PC recently discuss in private.
• The PC's brother comes fleeing to him after having killed a man in a drunken fit.
• The PC's father asks the PC to seduce a young woman of a rival family to disrupt a marriage.

Yes, there's more detail but it's how the details hit the PC that matters. A good moral crisis comes at something from several angles that will tear at the PC's conscience and force her to weigh her choices carefully. The trick is to juggle various factors. So focus on relationships and responsibilities, distribute the blame/guilt, and imbalance the consequences to the situation. The best moral decisions have no easy answers but need to be resolved. Related to resolutions is that fact that sometimes, okay a lot of the times, players will come up with either clever solutions or resolve the issue indirectly in ways you didn't foresee. This is great and should be encouraged. Just consider the realistic consequences of decisions and make your best guess.

One other point on this, it is important for the narrator and player to approach the campaign from an honest perspective when it comes to morality and ethics. These issues have been debated for thousands of years and will continue to be debated till humanity goes extinct. Don't force your ethics down the throat of your player. The best approach, and it can be a little tricky, is to focus on the reaction of NPCs to actions not philosophical points. One should also give the player the benefit of the doubt, if the player articulates a decent reasoning for why she is doing something then let the explanation not your assumptions determine the outcome.

Finally, there are directional decisions. These are very important in duets as they represent those decisions of the PC that shape the direction of the campaign. With group campaigns, there is very much a group/committee/railroad approach to charting out a campaign. With duets, the player through the PC is in control of where the campaign goes. This means sometimes you might end up way off script from where the narrator might have intended. This happens for two reasons: the player wasn't interested in the story arcs you provided or some alternative aspect of the setting is far more interesting. Usually it's both. Don't fight it, just run with it. In fact, directional decisions are sacrosanct in duet campaigns. If the player wants to do X, then you have to do X. If you would prefer the player does Y, then you need to sell Y not force it because the decision must always remain with the player when it comes to direction. This might lead a narrator to limit directional choices but this is a disservice to your player and yourself. You can handle a new direction and if the player has real choices to make about where the campaign is going then the player will be more invested.

In summation, the narrator needs to create a setting and story arc where the player is forced to make hard decisions, yet the narrator also needs to foster the conditions for the making of good decisions. There are lots of different sorts of decisions and each type requires a special blend to get right. The best way to master this is through experimentation; base your efforts on first thinking about what will truly test and engage the player in your particular campaign.